A lovely coincidence that I just finished writing down my own wishlist and was just about to post it when I saw yours. I love your immersion ideas, I think implementing them in one way or the other would be fantastic.
I both agree and disagree with your ideas of swordplay realism, athough MnB swordplay is awesome, I think it could be taken a step further without butchering it with microtweaks.
So, if you don't have nothing better to do with your time you might as well read my wishlist
The best thing about Warband was not the fact that it semi-accurately represented medieveal warfare, or that all combat was physics based, or even the sandbox aspect of the game.
No, it was the modality of the game. The fact that the vanilla game had limited to non-existent history, limited options as to character development and monodimensional quest lines didn‘t affect the endless array of mod-development options is simply fantastic.
I think modality should be taken to the next stage by allowing modders to add entirely unrealistic and fantastical elements (think flying mounts, with multiple passengers/operators, projectiles and such, giant characters, miniature characters, different species, non-humanoid characters) without actually putting them in the game itself so modders can take the framework and play around with it.
Don‘t get me wrong, I prefer Mount and Blade to remain entirely reality based, but those implementations will make fantastical mods such as The Last Days and A Clash of Kings so much better.
The fewer the limits, the better.
Battle size and formations
Of course Warband battle size was limited but that has to be improved upon in Bannerlord. Battle size of 400+ combatants per side should be realistic. That also means that battle organization must be improved. There should be a pre-battle planning and setup option, where the player can strategically place infantry, archery and cavalry to maximise the impact of every troop type. The player should also be able to give NPC‘s command within his party/army, so there will be a designated archery commander, infantry commander etc. who will fullfill a specific goal in the grand battle plan. The NPC‘s abiltities as a commander will be decided by his skill level. Spearmen are also heavily underpowered in Warband because Warband neglects the threat of a spear being pointed at you without it actually being thrusted towards anyone, which affects its efficiency in a formation.
Well, there‘s not much to be said here, but the Warband AI was simply retarded, even with modders modifying and changing the behaviour of the troops. Probably one of the most important aspects of the game that can be improved upon.
Feudality and management
A Kingdom or an Empire has to be efficiently managed. There should be a greater effect of the vassal system. A high ranking lord commanding a city should have a couple or more lords as his vassals managing the villages surrounding his lands, intstead of land simply being randomly awarded to lords once it is conquered.
There must also be a way of efficiently managing a large empire. When faraway settlements are conquered the king should be able to appoint a regional governor, who resides within the conquered regions greatest settlement and deals with local affairs instead of the king and the rest of the nation having to constantly travel back and forth when the need arises. This would mostly also affect mods with very large maps such as annus domini 1257.
Rebellions and civil wars
As most know, a state is not a single entity but a collection of numerous competing factions. When a lord grows powerful he might think to himself that he would make a greater ruler than the current king so he gathers support and enters into open revolt.
But warfare within factions should not be limited between kings and lords, it could also be waged between two lords, or a minor lord/landholder and his own liege lord or even the peasants and their owners. The results of such a war would usually end with the losing party being imprisoned, executed or banished from the lands.
And it should be entirely optional if the king or other lords decide to participate in those conflicts. The king may want to support a minor lord he likes againts a great lord he loathes, or the other way around, or maybe a lord would like to stab his rival in the back when he has trouble at home.
In such a scenario, there should be the possibility of an entirely different system of government, such as parliamentary autocracy, elective monarchy etc. Where different NPC‘s make up different parts of the social flora.
Strategic effect of buildings
One thing that has annoyed me throughout the Warband game is that castles and fortresses have almost no strategic impact. They just sit there. They should have their own command zone, and the ability to block acces through certain chokepoints. A castle commanding a choke point should be able to charge taxes from passing caravans, block hostile characters from entering their lands and prevent bandits from passing around freely.
There should also be a garrison commander within the castle, who estimates the risks and rewards of taking action. He may opt to ride out and stop a small band of bandits/mercenaries, but if a massive war party is passing through he will just cower behind the castles walls and wait for the threat to pass.
Some of those suggestions may be hard and impractical to implement, but they are still good food for thought.
As mentioned above, the way weapon usage was implemented in Warband heavily disfavours some weapons because they are not accurately used ingame. An axe has a greater array of movements than just the swing, it can also be used to hook legs, shields, limbs and weapons, a properly designed axe can also be used to stab with.
A spear is probably one of, if not the best field weapons there is in medieval warfare. The reason being is that having a pointy stick pointed towards your face is very uncomfortable. A spearman shouldn‘t have to thrust his weapon in order to damage the enemy, simply pointing it towards, lets say a charging horseman, should be sufficient. That also makes the implementation of spear formations more effective.
Historically, swords were not just hack and slash weapons, and rarely used as primary weapons, even by knight, unless we are talking about the great swords of the late medieval period of course. Swords were a status sign and for some reasons popular duelling weapons. Fighters would traditionally use the whole weapon in an array of techinques such as turning the weapon around and using the handle to hook as you would with an axe.
There needs to be a greater space for character development. In Warband the character usually progresses through a linear Commoner>Mercenary>Lord>King>Emperor progression, but there should be the possibility of becoming a great merchant (who interacts primarily with other merchants, tax authorities and bandits), a dedicated bandit or a bandit lord, a landowner, a dedicated sellsword, courtier etc. Although you can do all those things to an extent, dedicating a whole save game to these things in the current game is very bland.
There should be a greater variety of NPC‘s the player can interact with such as competing merchants, other mercenary bands, other adventurers etc. That will also affect the economy on a wholly different level.
There should also be a more immersive version of the Freelancer mod.
Naval warfare should be implemented, even if it doesn‘t fit the Calradian battlespace so it can be used by modders. The player should have to either buy a ship of his own, which he can crew with his own men or become a hired sword on a merchant vessel to protect its cargo. The vessels can then be captained by the character and NPC‘s, who‘s succes as naval commanders rests on their skill level. Then the character can either turn them into merchant vessels for his merchant fleet, or war boats for his navy. The character should have the option to build an independent navy once he becomes a lord of a coastal city or a King. Different troop types should also react differently to naval warfare. A Mongol based culture should not be the most efficient naval nation, but Nord raiders creeping up the rivers on longboats should have devastating effect on their enemies.
Sieges also need a lot of work. A greater tactical diversity is needed. This has more to do with the Battle size and formations part above though. Just a note, siege weaponry such as catapults were not very effective anti-personnel weapons, and it took them days, even weeks, to create a breach in a cities defences.
Marrying your character to lords and ladies is a relatively minor part of Warband that could be expanded upon. Firstly marriage should not be limited to nobility. It is againts the sandbox nature of the game, the character should have the option to marry a peasants or a merchants offspring as well to gain acces to their assets.
Player interaction to their partner and their relatives should also be greater, such as getting a loan from his father in law.
Relationships and husband/wife development should continue after the marriage ceremony, with the possibility of catching your partner in an affair, being caught having one such yourself and the effects of such events, such as divorce, imprisonment, retribution, protecting honour and all those Bold and the Beautiful soap opera events that make life.
This is probably the least important of my suggestions, simply because Warband surpasses almost every other game of its genre in terms of realism. But despite that there are many things that can be implemented without adversily affecting gameplay.
True death, aging and childbirth are heavily requested aspects that are very hard to implement simply because the amount of time spent playing the game by the character for those things to happen would be tremendous. One way to implement those things realisticly without spending your whole life on a single savefile is to have „cool down“ or „steady sailing“ periods over limited amounts of time. Every time, lets say when all the Calradian factions are at peace and the whole map reaches a relative stabilty the player has the option to „retire“ for a few years, until a time when a major political event occurs. During that period kids come of age, old people die etc. When the character dies he will be replaced by his heir.
Another issue is the renewal of dead characters. True death in combat would of course absolutely butcher the gameplay of the game, so in order to permanently kill an NPC one has to go through tremendous effort and risk. Quest lines where the character can kill a lord, merchant or even commit regicide should exist but the price of failure should be deer, even death.
Another issue is the renewal of dead characters. Of course there would be childbirth to replace dead characters, but every lord should have a retinue of NPC´s with him, who can rise to prominence themselves if the occasion arises. If their lord dies the NPC´s should scatter around the map and take up different objectives depending on their nature and loyalties, they may want to enter the services of another lord, start a mercenary company, become merchants or even enter the services of the player, so he can interact with NPC´s on a wholly different level than in Warband.
Ps. I understand that not all of the above are realistic, practical or fun. It is more food for thought than anything else to be honest.